Problem: Solve for $a$ : $-20 = -26 + a$
Explanation: Add $26$ to both sides: $ \begin{eqnarray} \\ \hphantom{-20 {+ 26}} &\hphantom{=}& \hphantom{a} \\ -20 &=& -26 + a \\ \\ {+26} && {+26} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ -20 {+ 26} &=& a \\ \end{eqnarray} $ Simplify. $ a = 6$